TORONTO – The line of Japanese reporters stretched outside the Yankees' clubhouse as if Friday were a postseason game. There were more of them grouped in front of the Yankees' dugout, still more inside the clubhouse itself, and a few more lingering in the Rogers Centre press box.

After months of breathless anticipation and international intrigue, the major-league debut of Yankees starter Masahiro Tanaka was surely going to be the baseball story of the night.

That was, until Mark Teixeira called for time out in the second inning and waved the Yankees' trainer onto the field.

Tanaka's rough-in-the-beginning but ultimately impressive debut might still be the biggest Yankees story in Japan, but after a 7-3 win against the Blue Jays, the more pressing issue in Yankee-land is the strained right hamstring that could land Teixeira on the disabled list just four games into the season.

Teixeira seemed to hurt himself while going after a foul ball. He initially stayed in the game before abruptly standing up straight in the middle of an at-bat and calling for manager Joe Girardi and trainer Steve Donohue. The three talked very briefly on the field before Teixeira walked off and into the Yankees' clubhouse.

An inning later, the Yankees announced that Teixeira had a strained hamstring. There was no immediate word on the severity of the injury or how much time Teixeira will miss, but the Yankees were banking on him returning from last year's wrist surgery and becoming a powerful middle-of-the-order force. They have no obvious replacement in place.

Third baseman Kelly Johnson is technically the second-string first baseman — and he took over the position on Friday — but moving Johnson only opens a different hole in the Yankees' already thin infield. Losing Teixeira also puts more of a burden on the Yankees' hard-to-predict pitching staff.

But Tanaka offered some hope in that department.

Against a dangerous Blue Jays lineup, Tanaka went seven innings, allowing three runs — two earned — walking none and striking out eight.

The first batter he faced was former Yankees outfielder Melky Cabrera, who welcomed Tanaka to the big leagues with a leadoff home run to center field. Three singles in the second inning — plus a Teixeira throwing error two batters before he left the game — gave Toronto two more runs and an early lead, but Tanaka was terrific the rest of the way. He struck out the last two batters in the second inning, beginning a final stretch in which he retired 16 of 18.

In his first meaningful game against major-league hitters, Tanaka seemed to pitch better as the game progressed, and the vast majority of his outs came either on strikes or on ground balls. Only two of his outs were hit in the air.

Tanaka went undefeated in Japan last season, and to help assure that he opened this season with the win, the Yanks' offense had its best game so far.

Five of their first six batters had hits. Jacoby Ellsbury reached base four times, Ichiro had his second straight multi-hit game, and spring-training revelation Yangervis Solarte had a two-run double right after the Yankees won their first replay challenge of the year, turning an Ichiro out into a hit.